In two days of hearings ending Wednesday, a federal committee proved quite skeptical about research that might help some patients birth healthy children — but might also open the door to human gene manipulation.

The procedure being considered, called mitochondrial transfer, would mix the genes of two women in hopes of creating a healthy baby.

Although the panel, which advises the federal Food and Drug Administration, did not take a vote, many members questioned the ethics of the procedure, and whether the research into it is as far advanced as some supporters claim.

Cell biologist Renee Reijo Pera, vice president for research and economic development at Montana State University, told her fellow committee members that she was very interested in the science of mitochondrial transfers, but isn't comfortable trying it in people.

"I just don't think that this is an avenue that we should pursue in humans," she added Wednesday via e-mail.

All people carry two sets of genes in every cell: the 20,000 genes in the cell's nucleus, which determine traits like height, eye color and intelligence; and the 37 genes in the mitochondria, which provide energy for each cell.

The mitochondrial transfer procedure would combine the nuclear genes from the mother with the mitochondrial genes of a donor woman. When fertilized, it would lead to babies with genetic material from three "parents."

The procedure promises to help women who carry defective genes that can lead to devastating mitochondrial problems in children, including blindness, organ failure and stroke. It might eventually also help resolve some types of infertility.

"These (people) really have terrible diseases and everybody wants to be able to treat them," said Evan Snyder, a stem cell biologist and head of the FDA's Cellular, Tissues and Gene Therapies Advisory Committee. "There is just not enough preclinical data to suggest how to do that and how to do it safely."

Dr. Evan Snyder(Photo: Sanford-Burnham Medical Research Institute)

The committee considered what scientists would need to do before they could try the technique in people, and whether it would be possible to design a clinical trial to answer the many outstanding questions about the procedure.

"Then we can see whether that's in any way feasible or acceptable," said Snyder, a stem cell biologist at the Sanford/Burnham Medical Research Institute in La Jolla, Calif. Snyder, also in the department of pediatrics at the University of California San Diego, said he does not think the committee or the FDA will address the topic again within the year, though it will likely come up again after more animal research has been completed.

David Prentice, a cell biologist and senior fellow for life sciences at the Family Research Council, a conservative advocacy group, told the panel he strongly objects to any mixing of genetic material.

"The individuals created are experiments," he said by phone after the meeting ended. "You're actually creating and destroying young human life which we object to. It just seems a very wrongheaded way to proceed."